1. Field of the Invention
The present invention relates to a water container for drinkable water, etc., and more particularly to improvements in or relating to the structure of water containers which are formed of a flexible material adapted to decrease the size thereof.
2. Statement of the Prior Art
One of the known water containers formed of a flexible material is illustrated in FIGS. 6 and 7, for instance.
The illustrated tank comprises a bag body 1 formed of a synthetic resin or the like, which is provided with a stopper 2. The stopper 2 is formed of a thin synthetic resin film (e.g., of a polyethylene film), and is of tubular form that includes a water inlet opening 21 and a valve opening 22, and is provided with a sealing 23 at a portion except for said openings. It is appreciated that the sealing 23 may be provided by superposing a pair of wall portions forming the stopper 2 one upon another and fusing it together with the application of heat and pressure, or alternatively superposing wall portions of the stopper 2 one upon another and bonding it together with the use of adhesives. The stopper 2 is attached to the container in such a manner that the water inlet 21 is open on the bag body, and other portion is located within the bag body. It is noted that one (as illustrated) or plural inlet openings may be provided.
Such a container can widely be used for the emergency, outing or like purpose since, when not in use, it can be folded up into a smaller size for storage. In use, the container may be supplied with a given amount of water through the stopper 2. That is to say, for instance, a water tap may be inserted into the inlet 21 in the stopper 2 to pour water. The thus poured water then reaches the valve opening 22, while expanding out the portion thereof except for the sealing 23 under the pressure of the water, and flows therefrom into the bag body 1 (indicated by an arrow in FIG. 6). As the bag body is filled with a given amount of water, the tubular stopper 2 is flattened together under the pressure of the water to prevent backflow of the water. The aforesaid sealing 23 is provided to facilitate flattening of the stopper. To remove the water, a user's finger or a pipe may be fitted into the stopper 2 to push it open. Or, when the container is of the throwaway type, the bag body may be cut open to this end.
However, the prior art water container offers problems in connection with air tending to enter with the poured water during pouring. Another problem arises in connection with water leakage, since the aforesaid flattening has only an insufficient effect on the prevention of backflow of water.